Magnetic brush-holder



(No Model.)

. J. G. HENRY. MAGNETIC BRUSH HOLDER.

No. 532,782. Patented Jan, 22, 1895.

Wnessesa fiZW7ZZ07T W X9 QWM Q UNITED STATES PATENT OFFICE.

JOHN G. HENRY, OF WVESTFIELD, NEW JERSEY.

MAGNETIC BRUSH-HOLDER.

SPECIFICATION forming part of Letters Patent No. 532,782, dated January22,1895.

Application filed December 11,1894. Serial No. 531,476. (No model.)

I a moving contact, such as a current collecting device, shall beproportioned to the work being done by the motor or the currentdelivered by the generator; or in other words, to

the transmitted current.

To attain these ends I actuate my brushes, in the form of holder which Iprefer, by electromagnetic means, giving a pressure proportioned to thecurrent.

In the operation of dynamo-electric machincry and particularly ofelectric motors, it has been'customary to press the brushes against thecommutator only by spring pressure, and this independently of the amountof work be- 1ng performed, or current delivered. This is objectionable,for although the conductivity is largely proportional to the pressure,and particularly so with carbon contacts, an excess of pressure whereonly small current is delivered acts to increase friction, to cut thecommutator and wear out the brushes, and inthe case of motors,particularly in streetcar work, to make a disagreeable screeching noise,besides acting as a more or less efficient brake, and thus decreasingthe commercial efficiency of the motor. To obviate these objections Imake my brushes preferably of carbon, although this is not essential,and I press each of them against the commutator by a spring which isjust sufficient to cause them to make contact. I also actuate them,either directly or indirectly by electro magnetic means co-operatingwith the spring, as by a solenoid having a core which backs up the brushand presses it against the commutator, or by an electro-magnet of anysuitable form and a system of levers or other gearing effecting the samepurpose. Preferably, though not necessarily, the electro-magneticarrange ments are in series in the circuit and as the current increases,the solenoids act with tion, of an electromagnetic arrangement of,

brushholders applied to a commutator. Fig. 2 is a modification showinghow a single magnet may operate both brushes.

Referring by letter, A is the shaft of the motor or dynamo-electricmachine.

B is the supporting disk or spider, and C is the commutator.

D, D are brushes,in the case illustrated, of carbon, though nothing inmy invention limits me to this material.

E, E are solenoids of which H, H are cores, only one of these beingshown, in the sectional view upon the right of the figure.

F, F are the casings or spools upon which the coils are wound, thecasings being made preferably of copper or other nonmagnetic metal.

G, G are the terminals of the line circuit. Any form of connection maybe used, and forms no part of my invention.

K is a spring pressing against the solenoid core H and through itholding brush D against the commutator, and I is an adjusting cap orscrew by which the pressure of the spring may be made just such anamount as will serve to carry the smallest current which the machine isadapted to deliver or utilize.

Referring now to Fig. 2, I illustrate substantially the same mechanismas in Fig. 1, except that a single solenoid E actuates, by means of ayoke M, levers N and bell-crank levers L, L, both of the brushes D, D.In this case the weight of the yoke M and the lovers maybe made j ustsufficient to give the brushes the amountof contact required, and thismay be assisted or lessened by the use of bearings as counterbalances inany desired way.

The use and operation of my improved device will be readily understoodfrom the foregoing description.

Vthat I claim as new, and desire to secure by Letters Patent of theUnited States, is

1. The method of effecting contact between the two parts of a currentcollecting device, which consists in causing the pressure of the contactto vary according to the variations of the transmitted current,substantially as described.

2. In combination, a current collecting device comprising a moving and astationary part, and electromagnetic means adapted to cause the twoparts to engage with pressure proportioned to the transmitted current.

3. In combination, a current collecting device comprising a moving partand a stationary part, and an electro-magnet in the main circuitpressing the two parts together; whereby the pressure between thecontacts is proportioned to the current transmitted.

at. In combination, a collector, brushes bearing upon the collector, andsolenoids actuating the brushes, the solenoids being in the maincircuit; whereby the pressure between the two contacts is proportionedto the current transmitted.

5. In combination, a commutator, brushes engaging therewith, solenoidsin the main circuit, and means connecting the solenoid with the brushesand adapted to press the brushes against the commutator with greater orless force according to the current transmitted.

6. In combination, a commutator, brushes engaging therewith, solenoidsin the main circuit, cores for such solenoids, and adjustable springspressing the cores against the brushes and thereby causing the brushesto engage the commutator with pressure proportioned to the smallestcurrent transmitted between the two.

In witness whereof I have hereunto set my hand this 30th day ofNovember, 189 i.

JOHN C. HENRY.

Witnesses:

C. J. BAscoM, M. H. FULLER.

